Amorpha nana aka Dwarf False Indigo

Amorpha nana is a small shrub in the pea family. Its common names include dwarf wild indigo and fragrant false indigo. It grows in central and west-central parts of North America. Its range includes southern Saskatchewan and Manitoba in Canada. In the United States, it reaches Colorado, Nebraska, Iowa, and Minnesota. It lives on dry prairies and rocky or sandy hillsides.

This shrub drops its leaves in autumn. Garden plants reach about 1.6–2 feet [0.5–0.6 metres] tall. They spread about 1.6–3.3 feet [0.5–1 metre] wide. RHS gives a lower height range than other garden sources. Its description also gives a height near 2 feet [0.6 metres]. The form may be upright, bushy, or low and spreading. Young shoots have red-brown skin and a few hairs. They lose these hairs as they age. The bright green leaves give the shrub a fine texture. Each pinnate leaf has many small leaflets along its stalk. Leaves measure about two to three inches long. The leaflets vary from narrow to broadly oblong.

Small purple flowers grow in racemes at the shoot tips. Each flower has just one petal. RHS describes orange flecks and a scent like honey. Flowering starts in late spring and continues into summer. Chicago Botanic Garden records blooms from May through August. The racemes measure about one and a half inches long. Small red-brown pods follow the flowers. Each pod holds one seed.

Grow this shrub in sun and soil that drains well. RHS recommends loam, but also lists sand and chalk. It accepts acid, neutral, and alkaline soils. Chicago grows it in dry soil; RHS allows moist, well-drained soil. Both sources support its use where water is limited. Chicago lists USDA zones 3–6, while RHS assigns UK rating H4. Plants take five to ten years to reach full size. Sow pre-soaked seed in spring or autumn in a cold frame.

Use it in borders, rock gardens, or prairie-style beds. Its spreading roots can help hold soil against erosion. PFAF also lists it as a nitrogen fixer. Pests rarely cause trouble, but rust and powdery mildew can occur. PFAF reports no known edible uses or hazards. It records a past use as snuff for catarrh. That record does not establish safe or effective medical use.